Detection of Meloidogyne graminicola (RRKN) in Kumaon region of the Indian Himalayas

Rice root-knot nematode (RRKN), Meloidogyne graminicola is a serious pest of rice (Oryza sativa L.) reported globally. In India, RRKN has been reported from various parts of the rice growing region and causing 17-30% yield loss. In the present study, RRKN population infesting rice growing region of Kumaon hills of Uttarakhand, Indian Himalayan region was isolated during 2019-20, characterized using integrative taxonomy by combining molecular analysis using ITS, morphology of male, juveniles, adult female and morphometry measurements of different stages. The data presented in the comparative analysis of morphometry parameters for Meloidogyne graminicola isolate from the Kumaon region of the Indian Himalayas, as compared to the original description by Golden and Birchfield (1965) from Louisiana, USA, reveals some differences in the morphological characteristics of adult females, adult males, and 2nd stage juveniles (J2) of M. graminicola. The ITS sequence from the present study appeared as a single clade between the Fujian isolate (KM111531.1) and the Brazilian M. graminicola isolate (KY962651). To our knowledge, this is the first authentic characterization and report of RRKN from the Hilly region of Uttarakhand state. The detection of M. graminicola in the mid Indian Himalayan region provides valuable information for further studies on the natural population dynamics and distribution patterns of this nematode species. The findings highlight the need for regular monitoring and surveillance of nematode populations in the region to better understand their distribution and potential impact on rice production.